1. Field of the Invention
The present invention relates to antennas, and, more specifically but not exclusively, to configurations of antenna assemblies in cellular applications.
2. Description of the Related Art
In conventional base-station installations, antenna assemblies and the base-station electronics that interconnect to them are separate physical entities. Antenna assemblies are mounted on cellular towers where they can have unobstructed views of the geographic areas they need to radiate into or receive from. Typically, an antenna assembly comprises one or more antenna arrays located behind a radome. When multiple antenna arrays are used, the antenna arrays may serve different frequency bands. For example, an antenna assembly may contain a first array that serves the 700-900 MHz band and a second array that serves the 1,850-2,170 MHz band. Antenna assemblies that serve multiple frequency bands are often referred to as “multi-band” antennas (or “dual-band” antennas when only two frequency bands are served).
The base-station electronics, such as Remote Radio Heads (RRHs), transmit outgoing (i.e., downlink) cellular electrical signals to the antennas and receive incoming (i.e., uplink) cellular electrical signals from the antennas. Base-station electronics are traditionally located inside a building such as a cell-site but or a small weather-proof enclosure at the base of the cellular tower. In this type of installation, the base-station electronics on the ground are interconnected with the antenna arrays on the tower using radio-frequency (RF) cabling.
As base-station electronics become smaller and more efficient, there is a trend to configure base-station electronics in close proximity to the antenna assemblies. For instance, Ericsson has developed an antenna assembly, referred to as the Antenna-Integrated-Radio (AIR), in which antenna arrays and their associated base-station electronics are all housed within a single radome. This implementation provides for reduced wind loading, better protection of the RF junctions from the elements, and a better aesthetic appearance.
Some cellular phone carriers have favored attempts to configure base-station electronics in close proximity to antenna assemblies. Other carriers, however, have resisted such efforts, preferring instead that the base-station electronics be installed on the ground.
Further, integrating the base-station electronics within the radome may be disadvantageous in situations when the electronics supporting one or more of the antenna arrays fails. In this situation, it may be necessary to (i) open the weatherproof enclosure of the radome to remove the failed electronics module, thereby exposing the other electronics within the radome to the elements, or (ii) remove the radome and associated electronics from the tower altogether. In addition, if the electronics supporting one or more other antenna arrays is still operational, then replacement of the failed electronics may require that service to the one or more other operational antennas be disrupted.